Electrical connectors designed to provide a reliable and secure contact retention, to preclude contact backout of connector housings are in wide use at this time. Such uses include particularly vehicular electrical systems where vibration and road shocks have been known to cause contact backout and electrical system failure. The prior devices typically include insulating housings equipped with lances protruding from the internal walls of the housing into the contact receiving chambers and additionally a double-lock device made of plastic which is inserted through a side wall of the housing to block contact backout. An example of a double-lock prior art publication wherein the locking operates by engaging the rear end of a contact may be found in Japanese publication No. HEI 1 (1989)-43986. An alternative retention of contacts is taught in Japanese publication No. HEI 1 (1989)-64872, wherein the insulating housing is arranged to clamp the contacts.
In yet a further alternative as taught in Japanese publication SHO64 (1989)-54678 and depicted as prior art in FIGS. 6 and 7 of this application, a double-lock device 13 is inserted into a wall la of an insulating housing 1. The double-lock device 15 has member 13 and projections 8 which fit into openings 6 of housing 1. Retention lugs 9 are on member 13 and lugs 10 are on the projections 8 and member 13, as shown in FIG. 6. Projections 10 fit within notches in a contact 3 in the side thereof and preclude withdrawal of the contacts or displacement and backout. Lugs 9, 9' latch device 15 into housing 1 as shown in FIG. 7. As also shown in FIG. 7 the referred to prior art contact 3 includes a latch 5 which latches internally of the housing and is one part of the double-lock system of retention.
Problems with prior art double-lock devices such as those referred to include tolerance variations in housings and contacts which result in an incomplete insertion of the contacts which can allow backout despite the double-lock features. Another problem relates to the use of spring elements on contacts which may be deflected inelastically to preclude functioning in holding the contacts in position during the insertion of double-lock devices in the housing. With respect to multi-way connectors, the need to fully insert all contacts prior to insertion of the double-locking device may be frustrated if a single contact is not fully seated. Still a further problem has to do with connectors which require more than two rows of chambers and contacts and particularly with those wherein the chambers and contacts are required to be staggered for the purposes of improved density or layout considerations.
Accordingly it is an object of the present invention to provide an electrical connector having double-lock features precluding contact backout which relate to improved reliability, ease of use and adaptation to connectors having more than two rows of chambers and contacts. It is still a further object to provide a double-locking electrical connector which allows the locking device to be retained in the connector prior to and during insertion of contacts and then activated further to effect the double-locking function.